Subject: Re: Requirements

From: "Joel M. Halpern" <[email-masked]>
Date: Sat, 20 Sep 2003 20:57:10 -0400

A large part of my problem with this requirement is that it leads sensible
implementors (such as yourself) to think that they need special protocol
mechanisms to support this.  It also leads sensible FE implementors to
think that they are somehow required to provide this implementation.

1) FE's better not be required to provide inter-FE topology information.

2) Allowing FEs which have such information to provide it does not require
special protocol mechanisms in any reasonably designed protocol.  CEs will
need to ask FEs for many pieces of FE level information.  If we must have a
requirement in this area at all, it should be a requirement that the set of
FE information a CE can query should include support for optional
information about inter-FE connectivity.  (A CE should not be required to
ask about this, an FE should not be required to provide this, and it really
should not be treated as special information requiring special protocol
support mechanisms.

Another way of looking at this is that there are many kinds of information
that an FE might be able to provide that might or might not be communicable
in the initial set of information mandated for CE-FE querying.  For lots of
reasons, the protocol MUST be extensible.  Making support of this
information important relative to selecting / defining the protocol seems a
serious mistake.

Yours,
Joel M. Halpern

At 05:35 PM 9/20/2003 -0700, you wrote:
>The text for this requirement has always been inter-FE topology (since
>v-02).
>I am pretty sure but I'll check with Todd anyways on this.
>
>If we do not provide protocol mechanisms to support this, then there
>will
>have to be non-standard ways to obtain this information from the FEs
>which
>provide this info, which we would like to avoid.
>
>Thanks
>Hormuzd

---

From: avri <[email-masked]>
Date: Sun, 21 Sep 2003 10:33:42 +0900

> 1) FE's better not be required to provide inter-FE topology 

It is not the FE that is required to provide the information.
It is the protocol that is required to provide a means for the FE to 
provide the information.  The two are very different.

> special protocol mechanisms in any reasonably designed protocol.

There has to be some mechanism.  While I prefer general mechanisms that 
allow for various kinds on info to be provided. I think this is one 
type of information that should be conveyed if available.

>  CEs will
> information about inter-FE connectivity.

What info is provided is optional.  The protocol mechanism should not 
be.

>  (A CE should not be required to

As I read it the FE is not required to provide it., Nor is the CE 
required to request it. The protocol is required to enable providing it.

> reasons, the protocol MUST be extensible.

Perhaps there are other sorts of information that would be useful for 
the FE to provide.  In which the mechanisms for providing this info 
should be flexible.  If the FE has this info because they have been 
configured by the FE manager to have it, it is only reasonable that 
there should be a way to convey it to the CE.

>  Making support of this

I disagree.  I think the protocol should be required to have a means to 
transfer any information that might be useful in defining the FE 
topology.

I am definitely in favor of leaving the requirement in.  And if the 
'best' protocol is best in all ways except that it it not able to 
transfer this information then the WG can consider whether it really 
cares at that time.  Personally I would prefer a protocol that did 
allow this information to be transfered.

a.